A method for improving high liquid limit soil using solid waste and its application

Abstract

The present invention discloses a method for improving high liquid limit soil by using solid waste and its application, which belongs to the technical field of solid waste recycling in roadbed construction and maintenance. In this method, recycled aggregate forms a skeleton structure to enhance the bearing capacity of high liquid limit soil; ultrafine cement realizes the solidification of high liquid limit soil and improves its strength; mineral fiber improves tensile strength, crack resistance and toughness; surfactant reduces the ion exchange capacity of soil and improves the lubrication effect of soil particles, thereby enhancing its ductility and water stability; bio-enzyme curing agent reduces the high liquid limit coefficient of soil and enhances the adhesion between high liquid limit soil particles. Starting from the purpose of improving the performance of high liquid limit soil, the proportion of each raw material is designed and the improvement process is optimized from the perspective of the role of each component in improving high liquid limit soil and its mechanism, thereby fundamentally improving the road performance of high liquid limit soil, thereby realizing the recycling of solid waste along the line on the basis of ensuring the excellent performance of high liquid limit soil, and achieving the dual benefits of resource conservation and environmental friendliness.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste recycling in roadbed construction and maintenance, and particularly relates to a method for improving high liquid limit soil by utilizing solid waste and application thereof. Background Art

[0002] With the rapid development of my country's economy, the number of cars has increased rapidly. Earlier-built expressways can no longer meet the needs of the growing traffic volume, making it imperative to renovate and expand these expressways in a timely manner. During renovation and expansion projects, a staggering amount of solid waste construction materials is generated along the routes. If these materials are not effectively recycled, they will not only require land for storage but also cause environmental pollution, undoubtedly bringing the dual pressures of resource waste and environmental pollution to society. The recycling and reuse of solid waste is a major trend in my country's expressway renovation and expansion projects. Research has shown that solid waste along expressway renovation and expansion routes can be processed through processes such as crushing and screening and then reused as recycled aggregate on-site in the project itself.

[0003] The present invention proposes a method for improving high liquid limit soil using solid waste. It not only breaks through the technical bottlenecks of the current high liquid limit soil improvement technology, such as the single technical means and poor improvement effect, but also realizes the recycling and reuse of solid waste along the line, saving resources and protecting the environment. It has great theoretical significance and engineering application value. Summary of the Invention

[0004] The object of the present invention is to provide a method for improving high liquid limit soil using solid waste. This method starts from the purpose of improving the performance of high liquid limit soil, designs the proportions of each raw material from the perspective of the effect and mechanism of each component raw material on the improvement of high liquid limit soil, and optimizes the improvement process, thereby fundamentally improving the road performance of high liquid limit soil. On the basis of ensuring the excellent performance of high liquid limit soil, the recycling of solid waste along the road is realized, achieving the dual benefits of resource conservation and environmental friendliness.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for improving high liquid limit soil using solid waste comprises the following steps:

[0007] S1. Select solid waste from the highway reconstruction and expansion project, crush it with a jaw crusher, and then screen it to obtain recycled aggregate with a particle size of no more than 2.36 mm and a particle size of 2.36-25 mm;

[0008] Select high liquid limit soil and measure its moisture content;

[0009] S2. Select a surfactant and a bio-enzyme curing agent and mix them in water to prepare a mixed solution A;

[0010] S3, selecting the recycled aggregate with a particle size of not more than 2.36 mm in S1 and ultrafine cement, dry-mixing and uniformly mixing to prepare a powdered mixture B;

[0011] S4, selecting the recycled aggregate with a particle size of 2.36-25 mm and the mineral fiber in S1, dry-mixing and uniformly mixing to prepare a mixture C;

[0012] S5. Add the high liquid limit soil in S1 into the blender, start stirring, and maintain the speed at 100-300 r / min; then slowly add the mixed solution A in S2 into the blender, stir for 2-5 minutes to mix, and then stop stirring;

[0013] S6. Add the powdered mixture B in S3 into the mixer, start stirring, maintain the speed at 100-300 r / min, and stir for 2-5 minutes; then add the mixture C in S4, continue stirring for 2-5 minutes to mix thoroughly, and obtain the improved high liquid limit soil.

[0014] Preferably, in S1, the high liquid limit soil is a plain soil with a liquid limit of not less than 50% and a plasticity index greater than 26; and a moisture content of 30-45%.

[0015] Preferably, the mass fractions of each raw material in the improved method are:

[0016] 100 parts of high liquid limit soil, 15-40 parts of recycled aggregate, 5-15 parts of ultrafine cement, 0.5-2.5 parts of mineral fiber, 1-9 parts of surfactant and 2-6 parts of biological enzyme catalyst;

[0017] The recycled aggregate includes recycled aggregate with a particle size of no more than 2.36 mm and recycled aggregate with a particle size of 2.36-25 mm;

[0018] The mass ratio of the recycled aggregate with a particle size not greater than 2.36 mm to the recycled aggregate with a particle size of 2.36-25 mm is 1:18-8:25, preferably 2:15-3:14.

[0019] The above-mentioned mixed aggregates of two different particle sizes are used because solid waste has both coarse and fine aggregates after crushing. Particles below 2.36mm are generally referred to as fine aggregate or powder, while those larger than 2.36mm are considered coarse aggregate, whose primary function is to form the skeleton structure. The performance indicators of the recycled aggregate meet the "Highway Engineering Technical Standard" (JTGB01-2014).

[0020] The above-mentioned mineral fibers are added according to volume ratio.

[0021] Preferably, the ultrafine cement is 425 ultrafine aluminum sulfate cement with an average particle size of 5-9 μm.

[0022] Preferably, the mineral fiber is chopped basalt fiber, with a single fiber diameter of ≤15 μm, a tensile strength of ≥4000 MPa, and an elongation at break of ≥3.0%.

[0023] Preferably, the surfactant is sulfonated castor oil.

[0024] The molecular formula of sulfonated castor oil is R-(SO2)OH-, which is composed of a negatively charged hydrophilic (i.e. (SO2)OH-) and a hydrophobic tail alkyl R.

[0025] Preferably, the bio-enzyme catalyst is weakly acidic tyranase with a pH value of 4.30-5.30 and a density of 1.00-1.08 g / cm 3 .

[0026] A method for improving high liquid limit soil by using solid waste is used in the preparation of high liquid limit soil improved by using solid waste.

[0027] An improved high liquid limit soil is obtained by treating it with the improvement method.

[0028] Compared with the prior art, the present invention has at least the following technical effects:

[0029] (1) The present invention provides a method for improving high liquid limit soil using solid waste. In this improvement method, the main function of the recycled aggregate is to form a skeleton structure and enhance the bearing capacity of the high liquid limit soil; the ultrafine cement solidifies the high liquid limit soil through the hydration process, thereby further improving the strength; the mineral fiber can significantly improve the tensile properties, crack resistance and toughness of the high liquid limit soil; the surfactant can reduce the soil ion exchange capacity and improve the lubrication effect of the soil particles while enhancing its ductility and water stability; the bio-enzyme curing agent reduces the soil high liquid limit coefficient and enhances the adhesion between the high liquid limit soil particles.

[0030] (2) This improved method is based on the recycling of solid waste generated along highway expansion and reconstruction projects. By combining the physical and chemical properties and functions of various raw materials, and determining their order of addition, a rational improvement process is developed. The raw materials are inexpensive and readily available, and the entire improvement process is simple, requiring only a simple mixer at room temperature, ensuring production efficiency.

[0031] (3) This improved method takes into account the road-use properties of high-liquid-limit soil, such as strength, toughness, water stability, and crack resistance, as well as its economic and social benefits, achieving significant economic, social, and environmental benefits. Taking into full account the special functional functions of long and large highway tunnels and the corresponding technical requirements, a modified high-liquid-limit soil is prepared by adding solid waste, treated with various additives, to high-liquid-limit soil using a specific process. This not only recycles the solid waste generated during highway reconstruction and expansion, conserving resources, but also saves land for solid waste storage, providing a new approach to the green and low-carbon construction concept of highway reconstruction and expansion projects.

[0032] (4) The improved high liquid limit soil can be used not only for the roadbed of highway reconstruction and expansion projects, but also for slopes and building construction, which greatly expands the application scope of high liquid limit soil and ensures the maximum recycling of solid waste along the line. DETAILED DESCRIPTION

[0033] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Specific conditions not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0034] Example 1:

[0035] A method for improving high liquid limit soil by using solid waste. The raw materials are composed of the following by mass ratio (mineral fiber by volume ratio): 100 grams of high liquid limit soil, 2 grams of recycled aggregate with a particle size less than 2.36 mm, 36 grams of recycled aggregate with a particle size between 2.36 and 25 mm, 6 grams of ultrafine cement, 1.0 (volume ratio) of mineral fiber, 0.3 grams of a surfactant, and 6 grams of a bio-enzyme catalyst.

[0036] The above-mentioned mineral fibers are calculated based on a volume ratio, specifically: based on the volume corresponding to the selected high liquid limit soil mass, the amount of mineral fibers is converted at a volume ratio of 1:1.0.

[0037] The high liquid limit soil is the plain soil at the renovation and expansion project site;

[0038] The recycled aggregate is the mineral material obtained by crushing and screening the solid waste along the highway reconstruction and expansion project with a jaw crusher;

[0039] The ultrafine cement is ultrafine aluminum sulfate cement;

[0040] The mineral fiber is chopped basalt fiber;

[0041] The surfactant is sulfonated castor oil;

[0042] The biological enzyme curing agent is weakly acidic tyranase.

[0043] In this embodiment, the steps of improving high liquid limit soil are:

[0044] (1) Determine the moisture content of high liquid limit soil;

[0045] (2) adding a surfactant, sulfonated castor oil, and a bio-enzyme curing agent into an appropriate amount of water in proportion to prepare a mixed solution A;

[0046] (3) Dry-mixing recycled aggregate with a size of less than 2.36 mm and ultrafine cement to obtain a powdered mixture B;

[0047] (4) Dry-mixing the recycled aggregate of 2.36-25 mm and basalt fiber to obtain mixture C;

[0048] (5) Add the high liquid limit soil into the mixer, turn on the stirring device, maintain the speed at 100-300 r / min, slowly add the mixed solution A prepared in step 2 into the mixer, stir for 2-5 minutes, and stop stirring;

[0049] (6) Add the powdered mixture B obtained in step 3 to the blender, start stirring, maintain the speed at 100-300 r / min, and continue stirring for 2-5 minutes;

[0050] (7) Add the product C of step 4 to the mixer of step 6 and continue stirring for 2-5 minutes to obtain the high liquid limit soil improved by solid waste.

[0051] Example 2:

[0052] A method for improving high liquid limit soil by using solid waste. The raw materials are composed of the following by mass ratio (mineral fiber by volume ratio): 100 grams of high liquid limit soil, 4 grams of recycled aggregate with a particle size less than 2.36 mm, 30 grams of recycled aggregate with a particle size between 2.36 and 25 mm, 8 grams of ultrafine cement, 1.3 (volume ratio) of mineral fiber, 0.25 grams of surfactant, and 5 grams of bio-enzyme catalyst.

[0053] The above-mentioned mineral fibers are calculated based on a volume ratio, specifically: based on the volume corresponding to the selected high liquid limit soil mass, the amount of mineral fibers is converted at a volume ratio of 1:1.3.

[0054] Example 3:

[0055] A method for improving high liquid limit soil by using solid waste. The raw materials are composed of the following by mass ratio (mineral fiber by volume ratio): 100 grams of high liquid limit soil, 6 grams of recycled aggregate with a particle size less than 2.36 mm, 28 grams of recycled aggregate with a particle size between 2.36 and 25 mm, 10 grams of ultrafine cement, 1.6 (volume ratio) of mineral fiber, 0.2 grams of surfactant, and 4 grams of bio-enzyme catalyst.

[0056] The above-mentioned mineral fibers are calculated based on a volume ratio, specifically: based on the volume corresponding to the selected high liquid limit soil mass, the amount of mineral fibers is converted at a volume ratio of 1:1.6.

[0057] Example 4:

[0058] A method for improving high liquid limit soil by using solid waste. The raw materials are composed of the following by mass ratio (mineral fiber by volume ratio): 100 grams of high liquid limit soil, 8 grams of recycled aggregate with a particle size less than 2.36 mm, 25 grams of recycled aggregate with a particle size between 2.36 and 25 mm, 12 grams of ultrafine cement, 1.9 (volume ratio) of mineral fiber, 0.15 grams of surfactant, and 3 grams of bio-enzyme catalyst.

[0059] The above-mentioned mineral fibers are calculated based on a volume ratio, specifically: based on the volume corresponding to the selected high liquid limit soil mass, the amount of mineral fibers is converted at a volume ratio of 1:1.9.

[0060] Example 5:

[0061] A method for improving high liquid limit soil by using solid waste. The raw materials are composed of the following by mass ratio (mineral fiber by volume ratio): 100 grams of high liquid limit soil, 10 grams of recycled aggregate with a particle size less than 2.36 mm, 25 grams of recycled aggregate with a particle size between 2.36 and 25 mm, 14 grams of ultrafine cement, 2.2 (volume ratio) of mineral fiber, 0.1 gram of surfactant, and 2 grams of bio-enzyme catalyst.

[0062] The above-mentioned mineral fibers are calculated based on a volume ratio, specifically: based on the volume corresponding to the selected high liquid limit soil mass, the amount of mineral fibers is converted at a volume ratio of 1:2.2.

[0063] Examples 2-5 adopt the improved steps, methods and treatment schemes in Example 1 above.

[0064] Table 1 Road performance of improved high liquid limit soil obtained in each embodiment and comparative example

[0065]

[0066]

[0067] The above comparative examples are compared based on Example 3.

[0068] Table 2 Road performance of improved high liquid limit soil obtained in each embodiment and comparative example

[0069]

[0070] Recycled aggregate, ultrafine cement, surfactants, enzymes, and mineral fibers work synergistically to comprehensively improve the road performance of high-liquid-limit soil. Coarser-grained recycled aggregate and ultrafine cement effectively increase the unconfined compressive strength and elastic modulus of high-liquid-limit soil, while sulfonated castor oil surfactant significantly improves its water stability, and enzyme curing agents effectively reduce its disintegration rate. Therefore, the method for improving high-liquid-limit soil based on the recycling of solid waste along highways, provided by this invention, is expected to enable the recycling of solid waste along highways during highway reconstruction and expansion projects.

[0071] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for improving high liquid limit soil using solid waste, characterized in that: The steps include: S1. Select solid waste from the highway reconstruction and expansion project, crush it with a jaw crusher, and then screen it to obtain recycled aggregate with a particle size of no more than 2.36 mm and recycled aggregate with a particle size of 2.36-25 mm; select high liquid limit soil and measure its moisture content; the high liquid limit soil is plain soil with a liquid limit of no less than 50% and a plasticity index greater than 26; and the moisture content is 30-45%; S2. Select a surfactant and a bio-enzyme curing agent and mix them in water to prepare a mixed solution A; S3, selecting the recycled aggregate with a particle size of not more than 2.36 mm in S1 and ultrafine cement, dry-mixing and uniformly mixing to prepare a powdered mixture B; S4, selecting the recycled aggregate with a particle size of 2.36-25 mm and the mineral fiber in S1, dry-mixing and uniformly mixing to prepare a mixture C; S5. Add the high liquid limit soil in S1 into the blender, start stirring, and maintain the speed at 100-300 r / min; then slowly add the mixed solution A in S2 into the blender, stir for 2-5 minutes to mix, and then stop stirring; S6. Add the powdered mixture B in S3 to the blender, start stirring, maintain the speed at 100-300 r / min, and stir for 2-5 minutes; then add the mixture C in S4, continue stirring for 2-5 minutes to mix thoroughly, and obtain the improved high liquid limit soil; The mass fractions of each raw material in the improved method are: 100 parts of high liquid limit soil, 15-40 parts of recycled aggregate, 5-15 parts of ultrafine cement, 0.5-2.5 parts of mineral fiber, 1-9 parts of surfactant and 2-6 parts of biological enzyme catalyst; The recycled aggregate includes recycled aggregate with a particle size of no more than 2.36 mm and recycled aggregate with a particle size of 2.36-25 mm; The mass ratio of the recycled aggregate with a particle size of no more than 2.36 mm to the recycled aggregate with a particle size of 2.36-25 mm is 2:15-3:14; The ultrafine cement is 425 ultrafine aluminum sulfate cement with an average particle size of 5-9 μm; The mineral fiber is short-cut basalt fiber with a single-filament diameter of ≤15 μm, a tensile strength of ≥4000 MPa, and an elongation at break of ≥3.0%; The surfactant is sulfonated castor oil; The biological enzyme catalyst is weakly acidic tyranase, with a pH value of 4.30-5.30 and a density of 1.00-1.08 g / cm 3 .

2. Use of the method according to claim 1 in preparing high liquid limit soil improved by utilizing solid waste.

3. An improved high liquid limit soil, characterized in that: Obtained by the improved method according to claim 1.

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